Someone who wasn’t quite so sure about the whole idea was my spaniel Tilly, but once she settled down, it was a great way to transport her to one of her favourite walking spots, about 3 or 4 miles away, against a strong headwind, and bring her back afterwards.

(The rattling noise is the little bench seat for children, which I’d folded back for this trip.)

The ideal transport for most families, my mother used to say, would be two small cars that you could bolt together to make one big car when you went on holiday. I still think she’s right, and I was pondering this last week when I came up with an idea I call ‘The Digital Towbar’….

Traditionally, if you wish to take your accommodation with you on a journey, you have the option of towing a caravan, or driving a campervan/motorhome. Both of these involve compromises.

Caravan owners have a suboptimal driving experience while towing, and may have to purchase a larger and less environmentally-friendly car than they would otherwise need. They also have to fit it with a towbar and related electronics. Motorhome drivers may have an even more compromised driving experience, and their accommodation must be fitted with a large engine and a driving cab. Some drivers even tow a car behind the motorhome for use at the destination.

Now imagine an alternative model, where your electric car is equipped with the battery capacity for its own use and the necessary sensors and processing power for full autonomy, but where it can also manage a self-powered trailer that follows behind. This trailer might be half-way between an electric motorhome and a caravan; it would not need a cab for drivers, nor would it need a full range of sensors and associated processing and navigational capabilities for independent self-driving. It would maintain a fixed distance behind the car, under the control of an ‘digital towbar’, and its sensors would report back to the car’s systems through the same link. (For the moment, I assume it will be a wireless link, though there may be advantages in having some sort of lightweight physical coupling: a USB cable, perhaps, or a power lead which could balance the usage across the two sets of batteries.).

Anyway, such a trailer could combine the best bits of a caravan — a space designed for comfortable accommodation rather than for driving — with those of a motorhome — a self-powered vehicle which doesn’t require your car to be able to move a load of several tonnes. Instead of towing a little car behind your motorhome, you could tow a motorhome behind your little car. In addition, once you’ve reached your destination, decoupling the two is trivial, leaving you free to explore the local area with ease.

Cars which support the necessary protocols would not need to be fitted with any special hardware or a large engine in order to ‘tow’ such a trailer, making the loan or rental of caravans easy. There are other advantages too: the challenges that novices face when reversing a trailer could be greatly simplified by a car that understands the physics, or could do the reversing itself. The trailer could even shift around to put itself next to you in an adjacent parking space, rather than always needing to be behind.

And, of course, this model of self-powered trailers is not restricted to caravans. Small cars could now add trailers with which to tow boats, bicycles, or just general add load-carrying capacity when moving house. You could even have a separate passenger trailer in which to put noisy children while the parents travel in peace. My mother’s idea may come to fruition after all!

Finally, a single car would not necessarily be limited to towing a single trailer at once. The family of the future may once again travel as a wagon train.

The hard part of standing on an exponential curve is: when you look backwards, it looks flat, and when you look forward, it looks vertical. And it’s very hard to calibrate how much you are moving because it always looks the same.

Just because we don’t have children, that shouldn’t stop us playing with toys, right? In fact, one of the benefits of our decision not to have children is that we arguably get to play with more toys. Yesterday, anyway, I tried one of these:

It’s an electrically-assisted cargo bike, which you could use for transporting the kids to and from school, if that’s your thing. But we were more interested in transporting groceries or spaniels around, while still avoiding parking & congestion issues, and making use of cycle paths and pedestrian bridges. The electric motor allows you to do so with no more effort than cycling a normal bike, regardless of hills, wind or weather.

It’s a splendid vehicle. Tilly was nervous at first, but seemed to enjoy sitting in it once we were zooming along a straight road at 15mph, with our ears flapping in the breeze, and we got lots of cheery comments from those we passed. Will have to come up with a good excuse to get one…

If you’re curious, it’s a Bakfiets Classic Short with Shimano Steps Electric Assist, model NN7STEPS, and it’s available, for example, from here. Not cheap in bicycle terms, but not bad when compared to a car, especially when you think of all the maintenance and tax savings…

At last! Today, I finally managed to leave the ranks of those who have never commuted to work on an electric unicycle.

Not sure I’ll make a habit of this mode of transport, especially since, as John points out, it is technically illegal here, but it’s a thing one should have done at some point in one’s life, I’m sure you’ll agree.

In my research group in the computer lab at Cambridge University, we have a few fun toys. This is one of them: an electric unicycle; there are a few different makes of these now, this one is a Ninebot One.

I’m not very good at it yet, but it’s great fun to learn – this is after I’ve been having quick goes on it occasionally for the last year or so.

It’s more fun outside. They’ll go to nearly 20 miles per hour. Haven’t been that brave yet…

You shouldn’t, of course, believe what you read in the papers. This is a good general rule, but recently we had a rather striking example. On Feb 11th, The Times ran an article entitled, “Electric cars mean UK could need 20 new nuclear plants”.

Here’s an extract, talking about a Transport for London report:

The analysis, seen by The Times, says that moving to an electric or hydrogen vehicle fleet “has implications for London’s energy supply system”. At the maximum level of uptake in the city green cars would demand between seven and eight gigawatt-hours per year. Experts said this was equivalent to the output of more than two nuclear power stations similar to that being built at Hinkley Point in Somerset. Extrapolated nationally, it would require the equivalent of 20 new nuclear power stations nationwide.

That’s a pretty memorable number – 20 new nuclear power stations! – and indeed, a family member who had seen it asked me about it, knowing my interest in the topic.

The trouble is, it’s just plain wrong. It was repeated in The Daily Mail, too, and Mail readers, bless them, are even less likely to have the critical faculties to question the headline…

I did some back-of-the-envelope calculations and things looked fishy, and it turns out that the original article is full of mathematical errors and lack of understanding. The first, and biggest, is that seven gigawatt-hours-per-year is not the same as seven gigawatts! Two Hinkley Points would indeed produce about 7 GW, but that is 7 gigawatt-hours-per-hour, not -per-year! So they were out by a factor of about 6000 immediately. However, many of the other figures quoted were also incorrect (some of them in the other direction).

If you’re interested in the real numbers, David Pellow’s letter to the Editor gives a much better analysis, but a quick summary is that yes, of course, we will need some more power generation when all of the UK’s 31M cars are electric, but if those cars are mostly charged overnight during off-peak periods, we could handle about 20M of them already just using the current power network.

This whole area is rather a fun topic, actually, and takes us into the realms of smart grids, home solar, grid-scale storage made from recycled batteries, and so forth. Cars are remarkably flexible about when, and how fast, they are charged, making them ideal for absorbing excess power and smoothing out the fluctuations of demand and of renewable generation. One day last year, Germany’s renewable sources of electricity produced so much power that they actually paid people to use it, and the problem of dealing with the peaks and troughs of demand is something that the power grids have had to struggle with for decades. Cars can actually help with this.

But I digress. What I actually wanted to talk about were a few other things that struck me about this story:

The Times has since published a brief retraction in the small print. I doubt this will remove the ’20 power stations’ idea from many people’s minds, though. Wasn’t there a proposal once that such corrections should be given the same font sizes and number of column inches as the original article? When I’m an MP, I’ll propose a bill to that effect…

The online version of the article has been edited to remove the dramatic claims, though the URL still reveals the original embarrassing headline. I can’t decide whether this is an admirable admission of error, or an attempt to rewrite history and pretend it never happened. What do you think?

The Daily Mail’s version of the story is still online, and I don’t believe they’ve published a correction at all. Should they be required to do so, when they were repeating another paper’s story which has since been retracted?

This is great news, though I’ve complained before that having an electric vehicle means you tend to spend more time in motorway service stations, and, frankly, if there’s one place worse than a motorway service station, it’s a petrol station forecourt. I’ll be much more enthusiastic when, say, the National Trust expands its laudable if rather meagre network of charging points, so I can charge my car while strolling through Capability Brown landscapes.

Still, a more ready availability of charging points anywhere is excellent news, and in-city petrol stations will certainly help those who want to own an EV but don’t have their own off-street parking — currently a significant barrier to electric adoption in cities.

I can’t help wondering, though, how petrol stations that still tell you it’s dangerous to use your phone in the vicinity of petrol fumes will cope with the 50-kilowatt 400-volt circuitry of rapid chargers… 🙂

One of the questions I often get asked about my car is, “Is it all-electric, or is it a hybrid?” For most EV owners, the answer to that is easy, but for the BMW i3, it’s a bit more complex. You see, it is a hybrid in the sense that it does have a petrol engine, but it’s also completely different from most of the Toyotas, Mitsubishis, Hyundais, etc. out there.

The i3 has a ‘Range Extender’ option (known as the REX), which is a little 650cc scooter engine, not much bigger than a melon, and a two-gallon petrol tank. The engine never drives the wheels directly, and in fact, it doesn’t even really recharge the battery, but it can keep the battery at a constant level of charge while you’re buzzing along. So if I have a battery range of 70 miles and I need to go, say, 120 miles with no charging points en route, here’s what I normally do: I put my destination into the satnav, and then glide silently out of town and onto the motorway. When my battery has depleted to about 50%, I turn on the REX, and use a bit of petrol until the remaining satnav distance is less than my remaining battery range, at which point I turn it off again. This means I only get the (small amount of) extra noise on the highway, where there’s plenty of other noise anyway, I keep pollution away from the populated areas, and I arrive silently at my destination, having used the minimal amount of petrol.

For me, it’s the perfect combination. I’ve now done about 12,000 miles in this car, and I’ve used less than 12 gallons to do so, which means my average MPG is still in four digits. In 5-10 years’ time, we’ll have much bigger electric ranges, without having to pay Tesla prices, and charging points will be sufficiently common that the petrol bit will be unnecessary. (Unless I move to a remote part of Colorado or Australia, I think I have probably purchased my last fossil-fuel-burning car.) At some point between now and then, one of the major petrol companies is going to install rapid chargers on all their forecourts. There’s a rumour that it might be Shell. This will be a brave thing to do, because it will instantly make EVs massively more attractive to the ordinary driver and will make a dent in the revenues of all the oil companies. On the other hand, this process is inevitable, so you want to be the company that does it first. I watch with interest…

But let’s get back to the hybrid discussion.

The challenge that plug-in hybrid designers face is how wholeheartedly to embrace the battery. You see, there’s a tipping point: you can’t sit on the fence. For most hybrids, you are building a normal car, and adding all the cost, weight and complexity of batteries and an extra motor. You don’t get enough electric range to use it as a real EV, though you might get some pretty impressive MPGs if, say, you charge each night and have a short commute. But when you’re running on the battery, you’re dragging around a lot of unnecessary metal and liquids. When on petrol, you’re carrying a lot of heavy battery. You need to keep a big enough engine to do everything people expect of a traditional car as well as fitting in a big enough electrical system to make the battery bit worthwhile. Minimalism it ain’t.

The beauty of pure electric vehicles, in contrast, is just how simple they are: no gearbox, exhaust, piston rings, tappets, crankshafts, oil sumps, filters, radiators, fuel-injectors, spark plugs, catalytic converters… all that messy stuff just goes away. I had originally planned to get a plug-in hybrid; the Golf GTE caught my eye when it came out, and I enjoyed test-driving one of the first ones in the UK, but I’d been spoiled by that point, because I’d also driven a couple of proper EVs, and I realised that they had to be the future. I often tell people that if you have (a) another car and (b) a driveway on which to charge, there’s no real reason now, when choosing a second car, for it not to be all-electric. The Nissan Leaf or Kia Soul EV are great vehicles, and I started to think I could get something like that for my normal day-to-day use and park my old Golf out of town somewhere, to be fetched when needed for long treks.

But for us, it would be silly to have two cars, which is why the i3 was the perfect solution. All the benefits of an EV, with no ‘range anxiety’ and very little extra complexity. Unfortunately, in Europe at least, BMW are currently the only company making this combination, which means that to get it, you have to pay BMW prices: quite a change for someone like me who spent much of their life crawling under elderly Minis or Beetles. I hope some other manufacturers catch on soon, but in the meantime, I do at least get the satisfaction of driving what Munro Associates described, a couple of years ago, for a whole range of reasons, as “the most revolutionary car in terms of creative engineering and manufacturing since Henry Ford’s Model T”.